NASA's Mars Exploration Rover Spirit took this panoramic camera image during Spirit's 152nd sol, on June 7, 2004. The rock, informally named "Plymouth Rock," is approximately 90 centimeters (35 inches) across and 50 centimeters (20 inches) tall. Spirit did not spend any time studying Plymouth Rock, but rover controllers used it as a guide to maneuver Spirit closer to the "Columbia Hills." Like most of the rocks found at the Gusev crater location, Plymouth is most likely a basalt. The tiny vesicles pitting the rock's surface further indicate its volcanic origin.